Rock boring cutter with thread-on replaceable cutting element

Abstract

A cutter with a replaceable cutting element is adapted to be mounted upon the rotary head of an earth boring machine or upon the body of an earth boring bit. The cutter is used in conjunction with an earth boring machine that functions to form a borehole or tunnel in the formation being bored. The cutter may operate to fracture rock between a proximate pair of kerfs in a manner to cause fragments of the formation to be separated from the formation being bored or may crush and disintegrate the formation. At least one annular cutting element is mounted on the periphery of the cutter body for contacting the formations. The cutter body includes an external annular threaded surface between the ends of the cutter body. The cutting element includes a threaded inner surface that mates with the threads on the cutter body. A locking shoulder on the cutter body is in contact with a locking shoulder on the cutting element.

The embodiments of an invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A cutter apparatus for earth boring, comprising: a saddle having a pair of support arms;   a bearing shell mounted between said support arms;   an inner cutter shell mounted for rotation about said bearing shell, said inner cutter shell having a generally tapered conical exterior surface;   threads on said generally tapered conical exterior surface of said inner cutter shell;   an outer cutter shell mounted over said inner cutter shell, said outer cutter shell having an outer surface and a central passage, said central passage having a conical surface;   threads on said conical surface of said central passage that engage the threads on said generally tapered conical exterior surface of said inner cutter shell; and   a multiplicity of carbide inserts mounted in said outer surface of said outer cutter shell.   
     
     
       2. A rolling cutter member for an earth boring system that functions to form a hole in earth formations, comprising: a saddle having a pair of support arms;   a bearing shell mounted between said support arms;   an inner cutter shell mounted for rotation about said bearing shell, said inner cutter shell having a generally tapered conical exterior surface;   threads along substantially all of said generally tapered conical exterior surface of said inner cutter shell;   an outer cutter shell mounted over said inner cutter shell, said outer cutter shell having an outer surface and a central passage, said central passage having a conical surface;   threads on said conical surface of said central passage that engage the threads along substantially all of said generally tapered conical exterior surface of said inner cutter shell; and   a multiplicity of carbide inserts mounted in said outer surface of said outer cutter shell arranged to form a series of annular rows.